* The present invention relates to copolymers of unsaturated carboxylic acids with other unsaturated compounds, a process for preparing same and the use thereof as a sequestering agent, complexing agent and co-buiIder in washing and cleaning agents.
Copolymers of unsaturated carboxylic avoids with other unsaturated compounds are known, for example from the German Patent Specification No. 19 04 940. Herein, copolymers of acrolein with acrylic acid have been described, which copolymers may be used as polycarboxylates as complexing agents.
Other polycarboxylates are known as copolymers of various unsaturated carboxylic acids. Thus, more particularly, there are known copolymers of acrylic acid, methacrylic acid and maleic acid and the use thereof as additives for washing and cleaning agents from the German Patent Specification (DE-PS) No. 26 16 261 and the German Published Unexamined Patent Applications (DE-OS) Nos. 29 10 133, 29 36 984, 32 33 775, 32 33 777, 34 26 368 and 36 04 223.
These polycarboxylates have gained increasing importance due to the introduction of low-phosphate or phosphate-free washing agents; cf. Diehl, "Phosphatfreies Waschen", Fette and Ole, Fettderivate, Folgeprodukte 112 (1986), pages 489 to 492, and Zini, "The Use of Acrylic Based Homo- and Copolymers as Detergent Additives", Chemieprodukte: Haushalt, Gewerbe, Industrie 83 (1987), pages 45 to 48.
A considerable disadvantage of the polycarboxylates used so far consists in that they are poorly biodegradable in sewage treatment plants. However, they are eliminated by absorption to the sewage sludge and, thus, will not get into the water. Similar products have been used for sewage sludge flocculation for years.*
The present invention relates to copolymers based on unsaturated carboxylic acids and monosaccharides capable of forming enolates. These copolymers are obtainable by copolymerizing the unsaturated carboxylic acids in an amount of from 35 to 80%, based on the total monomers, with an alkaline solution of the monosaccharides capable of forming enolates in the presence of free radical initiators at temperatures of between 60.degree. C. and 110.degree. C., while at least one of the two monomers is continuously supplied to the reaction batch, then cooled and precipitated by acidification. Furthermore, the invention relates to the use of said copolymers as a sequestering agent, complexing agent and co-builder in washing and cleaning agents.
It has also been found that, besides the monosaccharides capable of forming enolates, the disaccharides palatinose and leucrose are also capable of forming enolates and, thus, can be polymerized with unsaturated carboxylic acids in the same manner.
* An object of the present invention is to develop polycarboxylates which have an improved biodegradability and at the same time are inexpensive and may be produced simply and reliably.*
Another object of the present invention is to obtain in a simple way copolymers of unsaturated carboxylic acids by the reaction of monosaccharides capable of forming enolates with unsaturated carboxylic acids.
A further object of the present invention is to obtain copolymers of unsaturated carboxylic acids by the reaction of disaccharides capable of forming enolates, preferably palatinose and leucrose, with unsaturated carboxylic acids in a simple manner.
An additional object of the present invention is to achieve copolymer products which have favorable properties, such as calcium- and magnesium-binding capacities, for use as sequestering or complexing agents, or co-builders in washing and cleaning agents.
An advantage of the present invention is the production of copolymers using a mono- or di-saccharide component produced at reasonable cost from naturally reproducible raw materials.